A thermal camouflage sheet of this generic type is known from DE 297 16 362.
Camouflage nets are used for military camouflaging of fixed and mobile military facilities and devices, such as motor vehicles, armored vehicles and the like. The camouflage nets are in this case intended to achieve not only camouflage against infrared cameras or thermal imaging detectors, but also against radar detection. The camouflage net is in this case intended to prevent microwaves that strike an object from being reflected back from it. A further aim is to prevent the capability for identification by means of sensors in the infrared or thermal imaging band. For this purpose, a camouflage net has an appropriately matched hole structure in the network with a specific material composition, in order to provide protection both in the visible band and in the near infrared band, to achieve good attenuation levels over a broad spectrum in the microwave band, and to produce low emissions in the thermal imaging band (see, for example, DE 40 23 287 C2). Camouflage nets such as these generally satisfy their purpose. However, camouflaging is problematic when a hot spot occurs locally under the camouflage net, for example from the engine of a vehicle or else from a stationary engine. This local hot spot can be located on the basis of the network structure in the infrared band, for example in the far infrared band.
In order to avoid such identification, covering sheets are already known from practical use, by means of which the hot spot is covered. The known sheets have various disadvantages, however, for example poor mechanical strength and a restricted temperature range with a risk of burning if the temperature is too high. This results in restricted handling for rugged use in practice.
The document which forms this generic prior art describes a thermal camouflage sheet for covering heat sources, which has considerable improvements in comparison to the prior art mentioned above. The thermal camouflage sheet of this generic type has, on the side facing the object to be covered, a coating with a silicone elastomer which contains aluminum powder. The other side is provided with a silicone elastomer which contains metal pigments, whose remission values are in the visual-optical camouflage band. The thermal camouflage sheet is therefore effective within a wide temperature range, while having better mechanical strength and greater resistance to temperature at the same time.
In a further development of the thermal camouflage sheet of this generic type, however, it has been found that, despite the improved mechanical strength, fiber fractures and destruction of the coating can occur even at a relatively early stage, due to kinking. This is particularly true in a refinement of the thermal camouflage sheet of this generic type based on a warp knit. Furthermore, trials have shown that the thermal camouflage sheet of this generic type is subject to damage and/or is destroyed at the kink points when stored for lengthy periods. A further disadvantage of the thermal camouflage sheets which are coated on the basis of silicone elastomer is that the coloring is restricted in the visible band and in the near infrared (650 to 1250 nanometers). Furthermore, that surface of the thermal camouflage sheet which is coated with the silicone elastomer glistens, thus increasing the risk of discovery. A further disadvantage is that it is impossible to stick article numbers to that surface of the thermal camouflage sheet which is coated with silicone elastomer.
An improvement is likewise desirable with regard to the reflection on that side of the thermal camouflage sheet which faces the object to be covered, and which has a silicone elastomer coating that is provided with aluminum powder.
The present invention is therefore based on the object of overcoming the disadvantages of the prior art mentioned above, in particular of further improving the thermal camouflage sheets of the generic type, so that the capability to use and store the thermal camouflage sheets is improved, such that as far as possible all colors that also occur naturally can be simulated, and values in the infrared can largely be achieved corresponding to those in nature, while a matt surface can also be achieved.